Hydrogenation of alkoxy-substituted esters and products



Patented June 15, 1943 UNITED STATES PATENT OFFICE HYDROGENATION OFALKOXY-SUBSTI- TUTED ESTEBS AND PRODUCTS Donald J. Loder, William F.Gresham, and Donald B. Killian, Wilmington, Del., assignors to E. I. duPont de Nemours & Company, Wilmington, Del., a corporation of DelawareNo Drawing. Application February 24, 1939, Serial NO. 258,180

4 Claims.

R1-(:)O o o R;

wherein R is an alkyl, aryl, aralkyl, alkoxy methylene or alkoxyalkylidene group; R1 is hydrogen the groups in the R, R1, R2 and R3positions being the same as those given for the material treated. Theinvention relates to the hydrogenation of materials such as ((1.) alphamethyl ether of methyl glycerate, CH2OH.CH(OCH3).COOCH3;

(1)) alpha (methoxy methyl) ether of methyl glycerate,CHzOHCI-I(OCH2OCH3) COOLHa; methyl (methoxy methoxy) acetate,

CH2 (OCH2OCH3) COOCI-Ia;

(d) methyl methoxy acetate,

CH2(OCH3) COOCHa;

(e) isobutyl isobutoxy acetate,

CH2(OC4H9) COOC4H9;

and (f) Z-carboxymethyl-1,3-dioxo1ane,

cncoocm CH2-() to produce, respectively, (:11) glycerol beta methylether, CH2OHCH(OCH3)CHzOH; (b1) glycerol beta (methoxy methyl) ether,

CH2OHCH(OCH2OCH3) CHzOH;

(c1) methoxy methoxy) ethanol,

CHsOCHzOCHzCI-IzOI-I;

(d1) ethylene glycol monomethyl ether,

CH2 OHCHz OCI-Is (e1) ethylene glycol monoisobutyl ether,

CH2 (OH) CH2OC4H9;

and (f1) 2-oxymethyl-lB-dioxolane,

CHCHzOH OHg-0 An object of the invention is to provide a process for thepreparation of the above described compounds and their homologues. Theinvention further provides a process for the hydrogenation of the esteror carboxyl group of an alkoxy, aryloxy or substituted alkoxy or aryloxycompound to an alcohol group. Another object of the invention is toprovide a process for the conversion of alkoxy carboxylic acids, theiresters and derivatives to the corresponding glycol ethers. A furtherobject of the invention is to provide new glycol and glycerol ethers.Other objects and advantages of the invention will hereinafter appear. v

In general, the invention is carried out by bringing the alkoxycarboxylic compound and hydrogen into intimate contact with a suitab ehydrogenating catalyst under relatively hi h temperature and pressure,the reactants being in the liquid or vapor phase or both. There are,however, several modifications of the general process. For example, amixture of the compound to be hydrogenated, solid catalyst and gaseoushydrogen may be brought together with high temperatures and pressures ina closed autoclave capable of withstanding the necessary pressure. Whenoperating under such conditions, the catalyst is preferably acomposition containing copper, either in its elemental form or combinedwith oxygen as a lower oxide. Other hydrogenating metal oxides may beemployed in conjunction with copper, suitable catalyst supports such askieselguhr, silica gel, and activated carbon may be present. In afurther modification of the process, the alkoxy carboxylic compounds andhydrogen are passed under high pressures and elevated temperatures overmixed hydrogenation catalysts containing substantial quantities ofdiflicultly reducible oxides of hydrogenating metals prepared insuitable granular form and held in a pressure-resisting tube. Catalystssimilar to those disclosed in the copending application of A. T. Larson,S. N. 171,894, filed October 30, 1938, which describes copper catalysts,promoted or unpromoted with one or more metal oxides, may be employed.

The reaction proceeds in accord with the following equation:

It will be appreciated that, by substituting in the R, R1, R2 and R3positions, as has already been described, a number of materials can behydrogenated in accord with the invention to produce glycol others orglycerol ethers. It may be generally stated that the reaction involvesthe interaction of an alkoxy substituted acid or its ester or asubstituted .alkoxy acid or its ester to produce a corresponding etherof a polyhydric alcohol.

The process of the present invention may be effected at temperaturesranging between 150 and 350 C. and preferably between a temperature ofapproximately 175 and 250 C. The pressure may be maintained betweenapproximately 30 and 1000 atmospheres, with preferred pressures between400 and 700 atmospheres.

The more detailed practice of the invention is illustrated by thefollowing examples, in which parts are by weight unless otherwisestated. There are, of course. many forms of the invention other thanthese specific embodiments.

Example 1.A high pressure autoclave was charged with '75 parts of alphamethyl ether of methyl glycerateand .25 parts of methanol in thepresence :of a copper chromite hydrogenation catalyst (prepared byco-precipitating copper oxide and chromium oxide on kieselguhr andreduction of the dried catalyst with hydrogen). The temperature of thevessel and contents were raised to between 200 and 225 C. and hydrogenintroduced to give a pressure of approximately 600 atmospheres. Thereaction was continued until the absorption of hydrogen substantiallyceased, whereupon the hydrogenpressure was released, the hydrogenationproduct was fractionated to remove the methanol, and glycerol betamethylether (B. P. 118-120 C., 10 mm. pressure, specific gravity at 16 C.1.13) was recovered in practically quantitative yields.

Example 2.-The process of Example 1 was repeated using 50 parts of alpha(methoxy methyl) ether of methyl glycerate, 50 parts of methanol and 10parts of the copper chromite catalyst of Example 1. The temperature ofthe reaction was held between 200 and 250 C. and the pressure ofhydrogen maintained at approximately 600 atmospheres. The product wasrecovered as in Example 1 and after the distillation of the methanolpractically pure glycerol beta (methoxy methyl) ether (B. P. 124-12? C.at 6 mm. pressure) was obtained.

Example 3.--The process of Example 1 was conducted utilizing 69.8 partsof methyl (methoxy methoxy) acetate, and 106 parts of methanol, in thepresence of 20 parts of the copper chromite catalyst. At a temperatureof approximately 200 C. and a pressure of 600 atmospheres (methoxymethoxy) ethanol (B. P. 150-153 C. at 760 mm., specific gravity at 16C., 1.04) in approximately a 60% yield was obtained.

Example 4.-The process of Example 1 was repeated using 50 parts ofisobutyl iso-butoxy acetate, 50 parts of isobutanol and 10 parts of thecopper chromite catalyst. A good yield of the isobutyl ether of ethyleneglycol was obtained.

These products are useful as solvents for cellulose derivatives and asintermediates for the preparation of oxygenated organic compounds.

From a consideration of the above specification it will be realized thatmany changes may be made in the details therein given without departingfrom the invention or sacrificing any of the advantages that may bederived therefrom.

We claim:

1. A process for the preparation of glycol ethers which compriseshydrogenating an alkyl (alkoxy methoxy) acetate in contact with.a'hydrogenation catalyst at a temperature between 150 and 350 C. and ata pressure between 30 and 1000 atmospheres.

2. Methoxy methoxy ethanol.

3. An (alkoxymethoxy) monohydric aliphatic alcohol.

4. A process for the preparation of (methoxy methoxy) ethanol whichcomprises hydrogenating a reaction mixture of the approximatecomposition 69.3 parts of methyl (methoxy methoxy) acetate, 106 parts ofmethanol, and 20 parts of copper chromite to (methoxy methoxy) ethanol.

DONALD B. KILLIAN. WILLIAM F. GRESHAM. DONALD J. LODER.

